1. Field of the Invention
The present invention relates to construction materials, and particularly to an EAFD stabilizer for returned concrete and mixer drum wash water that uses Electric Arc Furnace Dust as a stabilizer, both as a stabilizer in concrete preparation, and also as a stabilizer for water used to wash out concrete drums, thereby providing an environmentally safe means of disposal for EAFD, which is a hazardous material, and recycling corrosive water that would otherwise be considered a hazardous material requiring containment on-site and disposal as a hazardous waste.
2. Description of the Related Art
Electric-Arc Furnace Dust (EAFD) is a waste by-product material generated during the steel manufacturing process at a rate of about 2% of the total steel output. The chemical composition of EAFD has been investigated by several researchers, and the most abundant heavy metals in EAFD were found to he Zinc (Zn), Lead (Pb), Chromium (Cr), and Cadmium (Cd). However, due to the leaching potential of the heavy metals contained therein, EAFD has been designated by the European Union (EU), and the EPA (United States Environmental Protection Agency) as a hazardous waste, which requires that EAFD must be treated prior to proper disposal in landfills. Therefore, finding effective and safe methods to discard large quantities of EAFD produced by the steel industry is a major environmental concern.
One possible solution has been to use EAFD to produce concrete. However, EAFD concrete could not be practically produced due primarily to the prolonged setting times of EAFD concrete. Such prolonged setting times can negatively impact the time and financial resources of a given construction project.
In the ready-mix concrete industry, it is a common practice to thoroughly clean the inside of a concrete truck's mixer drum at the end of each day. This may require 150 to 300 gallons of water. This wash water has a high pH and contains caustic soda and potash. Regulations require that concrete producers contain the mixer drum wash water on-site, and dispose of the water as hazardous material, unless the water is stabilized by chemical treatment.
In light of the above, it would be a benefit in the construction arts to provide a means of using EAFD in an economically practical manner that substantially reduces the environmental impact of EAFD stock, and to provide a way to stabilize mixer drum wash water to permit re-use of the water without harm to the environment. Thus, an EAFD stabilizer for returned concrete and mixer drum wash water solving the aforementioned problems is desired.